There are vertically articulated robots in which the wrist drive mechanism (a 5-axis drive mechanism in the case of a 6-axis multi-joint), which supports the wrist (a 5-axis portion in the case of a 6-axis multi-joint) from both sides by the wrist supporting portions provided at the end of the arm and vertically rotates the wrist, and the hand drive mechanism (a 6-axis drive mechanism in the case of a 6-axis multi-joint), which inwardly and outwardly rotates the end effector (a 6-axis portion in the case of a 6-axis multi-joint) arranged on the wrist, are coaxially arranged.
When the wrist drive mechanism and the hand-portion drive mechanism are arranged in the wrist supporting portion on the same side, the distance from the center of the arm becomes significantly different between the right and left sides. Therefore, in order to prevent interference when the robot is driven, it is necessary to set the interference prevention area with reference to the wrist supporting portion having a greater distance from the center of the arm. Consequently, the interference prevention area increases.
Patent Literature 1 discloses a robot that incorporates the hand drive mechanism in the wrist without the wrist drive mechanism and the hand drive mechanism being coaxially located. With this structure, the difference in thickness between the right and left wrist supporting portions supporting the wrist can be reduced compared with the case where the wrist drive mechanism and the hand drive mechanism are arranged on the same side.